Method and apparatus for improvements in the extrusion of metals and alloys

ABSTRACT

A method and apparatus for the extrusion of metals and alloys in an extrusion press wherein a lubricating disc about which an elastic band has been stretched is compactly placed in a tightly fitting manner in a substantially cylindrical shaped recess of a die holder which is ultimately positioned coaxially in the extrusion press so that the lubricating disc is between the die and the workpiece prior to the extrusion operation.

United States Patent [72] Inventor Erik G. Eriksson Sandvik, Sweden 21 App]. No. 883,111 [22] Filed Dec. 8, 1969 [45] Patented Jan. 11, 1972 [73] Assignee Cefilac Paris, France 54] METHOD AND APPARATUS FOR IMPROVEMENTS IN THE EXTRUSION OF METALS AND ALLOYS 5 Claims, 3 Drawing Figs.

[52] US. Cl 72/41 [51] Int. Cl 11211: 23/32 [50] Field of Search 72/41, 42, 43, 44, 45, 253; 207/101; 29/157 A; 252/10, 12, 122,124,126

[56] References Cited UNITED STATES PATENTS 3,021,594 2/1962 Clatot et al. 72/42 3,072,251 l/l963 Sauve 72/41 3,097,742 7/1963 Lamberty 72/42 Schieren Buntz et al.

Buffet Remus et a1. Griffen Sheasley... Schroeter.

Proctor FOREIGN PATENTS Primary Examiner-Charles W. Lanham Assistant Examiner-E. M. Combs Altorney- Webb, Burden, Robinson & Webb ABSTRACT: A method and apparatus for the extrusion of metals and alloys in an extrusion press wherein a lubricating disc about which an elastic band has been stretched is compactly placed in a tightly fitting manner in a substantially cylindrical shaped recess of a die holder which is ultimately positioned coaxially in the extrusion press so that the lubricating disc is between the die and the workpiece prior to the extrusion operation.

PATENTEU JAN! 1 I972 PRIOR ART /./V VE/V TOR. Erik Enks son in/v J14],

H/S ATTORNEYS METHOD AND APPARATUS FOR IMPROVEMENTS IN Til-IE EXTRUSION F METALS AND ALLOYS This invention relates to improvements in the method and apparatus for the extrusion of metals and alloys. More particularly, it relates to a lubricating disc and a method and apparatus for quickly and precisely affixing the disc to a die holder of the extrusion press.

It is well known that the extrusion of metals and alloys from a press requires a lubricant on the contact surface between the workpiece and the die. This is generally accomplished by plac ing a lubricating disc between the front end of the workpiece and the entry face of the die. The lubricating disc may be in the form of grains agglomerated with a binder. The diameter of the disc is generally substantially equal to that of the workpiece and the discs downstream face is designed to match the shape of the entry face of the die and die holder.

The die and die holder are generally detachably positioned at one end of the housing into which the workpiece to be extruded is placed. The die holder generally has a recess into which the die is placed. This die has to be frequently changed when extruding at elevated temperatures.

In horizontal extrusion presses which are capable of extruding a large number of workpieces per unit time, more than one die holder can also be employed. Where this is the case, a previously used die can be prepared for reuse by merely moving it away from the central axis of the press about which the workpieces are extruded. In general, the preparation of the die holder consists in inspecting the die, replacing it or, if appropriate, cooling and cleaning the die, and setting a new lubricating disc.

The lubricating disc has to be securely affixed on the die and die holder in a strictly coaxial position because any eccentricity results in a dissymmetrical compression of the disc when the workpiece is upset before the actual extrusion, as well as an uneven flow of the metal during the actual extrusion. This uneven metal flow then results in a product of undesired shape. This is especially true for tubes and other hollow sections.

Various methods have been proposed for affixing the disc. For instance, it has been proposed to attach elastic rubber trips to hook integral with the die holder so as to place them under tension on the front face of the disc. This may prevent the disc from falling down under the effect of gravity, but it cannot prevent the disc from being offset from its coaxial position by the shock sustained by the die holder when it bumps against the stoppers defining its working position.

It has also been proposed to place the disc on the die with an adhesive, but to do so, requires conditions that are not compatible with normal extrusion operations.

It has further been proposed to create a magnetic field, the forces of which cause the lubricating disc to adhere to the die and die holder. This requires the inclusion of intricate equipment in the die and die holder. This, of course, is expensive and is especially so where consumable dies are employed. Further, this requires using magnetic materials in the lubricating discs which, of course, are only used once.

My invention overcomes these above-mentioned disadvantages. My invention permits the lubricating disc to be securely affixed to the die holder and to be maintained in a strictly coaxial position with the working axis of the extrusion press. Further, my invention permits accomplishing these results without complication and with a minimum of expended time and effort.

My invention comprises positioning a tightly fitting elastic band around the cylindrical periphery of the disc and then compactly inserting this resultant disc assembly into a substantially cylindrical shaped recess in the die holder.

In the accompanying drawings, 1 have shown one preferred embodiment of my invention in which:

FIG. 1 is a section through the downstream end of an extrusion press according to the known practice;

FIG. 2 is an exploded view in section of a die holder arrangement according to my invention; and

FIG. 3 is a section through the die holder of FIG. 2, but which is in position for extrusion.

The downstream end of a typical known horizontal extrusion press is shown in FIG. 1. The housing 1 which holds the workpiece 5 to be extruded is securely sealed coaxially onto the die holder 2. The removable die 3 is inserted into a recess of the die holder 2. In this case, the die corresponds to an L- section to be extruded. A lubricating disc 4 rests on the lower inner surface of the housing I as does the workpiece 5. The entry face of the die holder 2 has a frustoconical edge 6. The coaxial center line 12 of the housing and die holder is also shown.

My invention, which is an improvement over the known practices of FIG. 1, is shown in FIGS. 2 and 3. The die holder 10 has a frustoconical surface 11 similar to the surface 6 of FIG. 1. However, the frustoconical surface 11 connects with a cylindrical surface 7, the diameter of which is substantially equal to that of the housing 1 (see FIG. 3). The die 3 is shown in place in the die holder 10. A band 8, made of an elastic material such as rubber, is stretched over the cylindrical surface 9 of the lubricating disc 4. The assembly formed of the band 8 and disc 4 is forcibly inserted into the cylindrical section 7 of the die holder 10 so it is compactly held therein.

The cylindrical section 7 of the die holder 10 need not be perfectly cylindrical and may only approach being cylindrical such as by being replaced by a section in the form of a slight frustum. The nonparallel surfaces of the slight frustum, if imaginarily extended, should not intersect the central axis 12 at an angle greater than 5 and preferably in the order of 1 or 2. The larger base of the frustum should face the lubricating disc as it approaches. Such a design makes it easier to insert the lubricating disc 4 and band 8 and also permits an easy removal of the extrusion discard from the die holder 10 after extrusion. The angle to the axis of the slight frustum section must be small as indicated to prevent the biasing component of the band from ejecting the disc.

A typical elastic band 8 would be made of rubber and be about 2 mm. (0.08 inch) thick and 3 to 10 mm. (0.12 to 0.40 inches) wide.

The following example of my invention resulted in the use of lubricating disc which were securely affixed in the die holder.

An extrusion press had a housing for the workpiece with a diameter of 289 mm. (11.40 inch). The die holder had a frustoconical section having an angle of 45 to the central axis and a height of 10 mm. (0.40 inch). The frustoconical section connected into a slight frustum section (substantially cylindrical) for the disc assembly having a smaller base 288 mm. (11.36 inch) in diameter, a larger base 289 mm. (1 1.40 inch) in diameter and a height of 15 mm. (0.60 inch). The particular discs employed were either solid or hollow depending on the desired end product. The discs were made of agglomerated glass powder and were 25 mm. (1 inch) thick and 285 (1 1.24 inch) in diameter. The downstream edge of the disc was chamfered at 45 on 9 mm. (0.36 inch). The elastic band was rubber and its outside diameter at rest was 286 mm. (11.28 inch). The discs radial thickness was 1.5 mm. (0.06 inch) and their width was 5 mm. (0.20 inch).

An inspection of the extrusion discards showed that the lubricating discs were perfectly centered (coaxial with the housing) when being compressed.

I claim:

1. In an extrusion press for metals and alloys having a die held in position by a die holder and in which the die is separated from a workpiece to be extruded by a disc of lubricating material, the improvement comprising:

A. A substantially cylindrical recess in the die holder, said recess being located so that the lubricating disc enters the recess before contacting the die face; and

B. An elastic member stretched tightly over the periphery of the disc to form a disc assembly, the disc assembly being dimensioned so that it can be compactly positioned into said recess.

2. The improvement of claim I wherein the substantially cylindrical recess forms an angle of less than 5 with the central axis of the extrusion press.

and in which the die is separated from a workpiece to be extruded by a disc of lubricating material, the improvement comprising:

A. Stretching an elastic band tightly about the cylindrical periphery of the lubricating disc to form a disc assembly; B. Inserting the disc assembly compactly into a substantially cylindrical recess in the die holder; and C. Extruding the workpiece. 

1. In an extrusion press for metals and alloys having a die held in position by a die holder and in which the die is separated from a workpiece to be extruded by a disc of lubricating material, the improvement comprising: A. A substantially cylindrical recess in the die holder, said recess being located so that the lubricating disc enters the recess before contacting the die face; and B. An elastic member stretched tightly over the periphery of the disc to form a disc assembly, the disc assembly being dimensioned so that it can be compactly positioned into said recess.
 2. The improvement of claim 1 wherein the substantially cylindrical recess forms an angle of less than 5* with the central axis of the extrusion press.
 3. The improvement of claim 1 wherein the substantially cylindrical recess has a diameter substantially equal to that of the opening of a main housing, said main housing being sealably secured to the die holder to hold the workpiece prior to extrusion.
 4. The improvement of claim 1 wherein a frustoconical section connects with and is positioned inward of the substantially cylindrical section.
 5. In a process for the hot extrusion of metals and alloys in an extrusion press having a die held in position by a die holder and in which the die is separated from a workpiece to be extruded by a disc of lubricating material, the improvement comprising: A. Stretching an elastic band tightly about the cylindrical periphery of the lubricating disc to form a disc assembly; B. Inserting the disc assembly compactly into a substantially cylindrical recess in the die holder; and C. Extruding the workpiece. 